The NAM discovered during measurements that there is too much of the chemical substance Toluene in the wastewater. According to the company, these are small exceedances that are harmless in the measured quantities.
The fact that NAM has stopped oil extraction and the injection of waste water after all is because the company wants to comply with the permit conditions.
Toluene, also known as methylbenzene, is a volatile chemical liquid. It is used, among other things, as a diluent and as a raw material in chemistry. Toluene is the main component of thinner. It is also a component of gasoline and is used as a solvent in tire adhesive. With prolonged exposure to high concentrations, Toluene is harmful, it can cause memory problems. In the short term, Toluene is harmful because inhalation of large amounts can cause dizziness and nausea. Breathing in can even make you unconscious.
No oil extraction
According to a spokesperson for the NAM, Toluene occurs naturally in small quantities in oil and gas fields, including the largely depleted gas field below Rossum. “The levels of Toluene in the production water are about 1 millionth of the total amount.”
The exceedance of the limit values for Toluene was found in the waste water in Schoonebeek. Because NAM wants to continue to work strictly within the permits, the company was forced to temporarily shut down oil extraction in Schoonebeek. This also gave the company the opportunity to perform other activities in the meantime.
Employees are now applying a special coating to a water storage tank at the oil treatment plant in Schoonebeek. According to the spokesperson, the storage tank is necessary to achieve an optimal separation between the extracted oil and the waste water.
Bacterial problems in the piping system
According to project leader Vincent van Engelen, applying the coating has nothing to do with the bacteria that eat into the steel wall of the piping system. This coating is purely to protect the steel on the inside of the storage tank.”
It has been known for some time that the NAM is dealing with a persistent bacteria in the wastewater, which means that the wastewater pipe system runs the risk of leakage. The warm waste water also contains a lot of sulphates, the acid residues of sulfuric acid and its salts.
The sulphate-reducing bacterium loves these substances and appears to be very difficult to combat. Because these bacteria attach themselves to the steel inner wall of the pipe system and eat into the steel, NAM has already had to deal with leakage.
This leakage was discovered in 2015 in the transport pipeline that carries the waste water from Schoonebeek to Twente. At the time, oil extraction and therefore wastewater injection were also stopped for a long time. NAM invested millions in a new plastic pipe system that was installed in the old pipes. This would prevent the bacteria from coming into contact with the steel pipes.
The coating has previously been used in the fight against the sulphate-reducing bacteria, but that did not help. That is why the NAM has meanwhile replaced the most important parts in the installation with stainless steel, as the bacteria has no grip on such hard steel. Van Engelen is hopeful that this intervention will provide a solution in the fight against the bacteria.
The NAM expects that the problem with the exceeding of the limit values for Toluene will be solved by the end of January. With minor technical adjustments, NAM hopes to be able to restart oil extraction at the end of this month. In that case, wastewater will immediately flow back into the soil of Twente.
Majority of the House of Representatives wants to stop injection
A majority in the House of Representatives wants the minister to stop the injection of waste water. A motion on this was passed in December, but the Minister of Economic Affairs does not want to implement it. According to him, the Nederlandse Aardolie Maatschappij adheres to the permit conditions and there are no legal grounds to intervene. Several MPs are disappointed about this and again asked parliamentary questions.